ams: update build system to add generic-fallback support

Switch atmosphere's build target to C++20. (#952) ...

* ams: update to build with gcc10/c++20

* remove mno-outline-atomics

* ams: take care of most TODO C++20s

* fusee/sept: update for gcc10

* whoosh, your code now uses pre-compiled headers

* make: dependency fixes

libstratosphere: use from /atmosphere/libraries

Improve exception wrapping

Results: Implement namespaced, type-safe results. ...

Because I was working on multiple things at once, this commit also:
- Adds wrappers for/linker flags to wrap CXX exceptions to make them
  abort. This saves ~0x8000 of memory in every system module.
- Broadly replaces lines of the pattern if (cond) { return ResultX; }
  with R_UNLESS(!cond, ResultX());.
- Reworks the R_TRY_CATCH macros (and the result macros in general).

boot: move updater into libstrat

boot: split out gpio, pinmux.

boot: refactor i2c driver into namespace

stratosphere: more result cleanup

boot: implement CheckAndRepairBootImages

boot: functional exception handling/rebooting to payload

boot: add i2c device configs

boot: prepare for rewrite of boot sysmodule

Add defines for atmosphere git revision.

atmosphere: extract API version management to common folder

boot: build as KIP (thanks @fincs !)

Boot: Initial skeleton and 1.0.0 GPIO voltage switch.